MIPS: BREAK instruction interpretation corrections

Add the missing microMIPS BREAK16 instruction code interpretation and
reshape code removing instruction fetching duplication and the separate
call to `do_trap_or_bp' in the MIPS16 path.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9696/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>